//
// detail/completion_handler.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_DETAIL_COMPLETION_HANDLER_HPP
#define ASIO_DETAIL_COMPLETION_HANDLER_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"
#include "asio/detail/fenced_block.hpp"
#include "asio/detail/handler_alloc_helpers.hpp"
#include "asio/detail/handler_work.hpp"
#include "asio/detail/memory.hpp"
#include "asio/detail/operation.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
    namespace detail {

        template<typename Handler, typename IoExecutor>
        class completion_handler : public operation {
        public:
            ASIO_DEFINE_HANDLER_PTR(completion_handler);

            completion_handler(Handler &h, const IoExecutor &io_ex)
                    : operation(&completion_handler::do_complete),
                      handler_(ASIO_MOVE_CAST(Handler)(h)),
                      work_(handler_, io_ex) {
            }

            static void do_complete(void *owner, operation *base,
                                    const asio::error_code & /*ec*/,
                                    std::size_t /*bytes_transferred*/) {
                // Take ownership of the handler object.
                completion_handler * h(static_cast<completion_handler *>(base));
                ptr p = {asio::detail::addressof(h->handler_), h, h};

                ASIO_HANDLER_COMPLETION((*h));

                // Take ownership of the operation's outstanding work.
                handler_work <Handler, IoExecutor> w(
                        ASIO_MOVE_CAST2(handler_work < Handler, IoExecutor > )(
                                h->work_));

                // Make a copy of the handler so that the memory can be deallocated before
                // the upcall is made. Even if we're not about to make an upcall, a
                // sub-object of the handler may be the true owner of the memory associated
                // with the handler. Consequently, a local copy of the handler is required
                // to ensure that any owning sub-object remains valid until after we have
                // deallocated the memory here.
                Handler handler(ASIO_MOVE_CAST(Handler)(h->handler_));
                p.h = asio::detail::addressof(handler);
                p.reset();

                // Make the upcall if required.
                if (owner) {
                    fenced_block b(fenced_block::half);
                    ASIO_HANDLER_INVOCATION_BEGIN(());
                    w.complete(handler, handler);
                    ASIO_HANDLER_INVOCATION_END;
                }
            }

        private:
            Handler handler_;
            handler_work <Handler, IoExecutor> work_;
        };

    } // namespace detail
} // namespace asio

#include "asio/detail/pop_options.hpp"

#endif // ASIO_DETAIL_COMPLETION_HANDLER_HPP
